Depends on the cas latency of each vs throughput but from looking at these id say the Dominator would be your best bet for gaming, 8 gigs wont do you a lick of good unless your running multiple intensive tasks as brinks said.

so you gain 1-2 fps, depending on the app, but will you notice it? nawwwwwwwwwwwwwwwwwwww
will your wallet notice $100 dollar less? probably yes.
unless you are so rich, a hundred bucks doesn't matter at all. then go for the GT's, looks nice and you get bragging rights.